1. Field of the Invention
The present invention relates to the outer soles of sports shoes, having through-holes passing through a lateral surface of the sole, a method for their manufacture, and an apparatus for their molding, More particularly, the present invention relates to the outer sole of sports shoes wherein by forming the through holes so as to extend through a lateral surface in the side direction of the midsole, as well as by reducing the weight of the shoes, it is possible not only to increase the cushioning effect of the shoes, without using air cushions, but also to have the desirable effect of insulating the wearer's feet, since the through-holes serve to separate the foot from the ground while the shoes are being worn.
2. Discussion of Related Art
It is well-known that it is desirable to make conventional outer soles of sports shoes lightweight and, in order to make them comfortable and provide a cushioning effect, an air cushion is used in the manufacture of the midsole of the shoe. In manufacturing such outer soles, however, additional work is necessarily required in order to provide an additional air cushion on the mold in which a midsole is formed, and also since these air cushions require additional work prior to assembly of the soles to inflate the cushions with air or gas, it has caused an increase of the manufacturing cost as well as an increase in the defective rate of goods and it has a drawback in that the shoes lose their function as sport shoes if the air cushion deflates after wearing the shoes.
Currently, as a way of manufacturing the midsole in the outer sole of sports shoes, it has been used that since it is formed at the state that the midsole is placed horizontally, it is molded in a shooting method normally by raising it onto upside and inserting resin, which is used to be shot, to the mold of molding consisting of the 2nd or 3rd stage and heating it up to a fixed temperature.
Accordingly, a structure of a mold for the manufacture of shoe outer soles, as shown in FIG. 9, has been used as a way of manufacturing the outer sole of sports shoes that the middle stage mold 200, which is positioned adjacently upwardly from the lower stage mold 100 and the higher stage mold 300 in which a protrusion 600 is formed, are raised sequentially upwardly.
Also, in order to increase the cushioning force as well as to reduce the weight of shoes today, as shown in FIG. 9, the molding operation is performed by injection molding, wherein a protruding pin 400 is formed so that an air cushion may be placed in the side partition of the mold and then attaching the air cushion by inserting an air cushion between the side partition of the mold and a protruding pin 400, or an air cushion is mounted on the midsole, which is molded, by mounting the air cushion into an inserting tube 500 which is first formed.
There is, however, a drawback in that, since additional air or gases are not inserted into an air cushion, and in the case that the air cushion is deflated, the cushioning function of the shoes is significantly reduced.
Another drawback is that these kinds of air cushions are costly and expensive due to the cost increase since the air cushions must be specially made for this purpose.